You need to verify the electronic primer is operating. Remove the outlet hose from the primer, put a short temporary hose on the nipple, aim the temp hose into a bottle, turn the key to crank the engine, then immediately press in on the key and hold for about about 5 seconds. If the primer is working properly you should have a nice accumulation of fuel in the bottle. If there is no fuel in the bottle you need to troubleshoot your primer wiring and ensure you are getting 12V to the primer when the key is pressed in. If you get 12V on the connector, then your primer solenoid is bad. If there is not 12V, then you have some searching to find the culprit.
To cold start my 1996 Evinrude 150 I squeeze the primer bulb until firm, turn the key to start and after about 1 second I press in. The engine starts every time and stays running. Once you ensure your electric primer is working, this starting sequence should work for you.